1) Field of the Invention
The present invention relates to a paper feeding method and an apparatus therefor, wherein papers are selectively fed to a paper-processing station through at least two paper guide paths. The present invention also relates to a printer in which such a paper feeding apparatus is incorporated.
2) Description of the Related Art
Unexamined Japanese Patent Publication (KOKAI) No. 62(1987)-99171 discloses a printer having a paper feeding apparatus incorporated therein, which comprises first and second paper guide paths for selectively feeding a continuous form paper and a cut sheet paper, respectively, to a printing position defined by a platen and a printing head of the printer, and a mechanical switching system for selecting one of the first and second paper guide paths so that a double feeding of the papers to the printing position can be prevented.
The first paper guide path for the continuous form paper is formed of a guide plate member disposed between the platen and a pin-belt tractor in which the continuous form paper to be fed is set. As is well known, the pin-belt tractor includes a pair of endless belts having a plurality of pin elements which are engageable with two rows of perforations formed along the side margins of the continuous form paper. By driving the pin-belt tractor, the continuous form paper is fed to the printing position through the first paper guide path. The platen and the pin-belt tractor are driven by a common drive motor, but the operative connection between the pin-belt tractor and the platen can be selectively cut by the mechanical switching system.
The second paper guide path is formed by partially applying a guide member to the platen, and joins the first paper guide path at a location adjacent to the platen. The cut sheet paper is manually introduced into the second paper path, and is then fed to the printing position by a pressure roller resiliently pressed against the platen driven by the motor. In particular, a leading edge of the introduced cut sheet paper is abutted against a nip between the platen and the pressure roller, and the cut sheet paper is passed through the nip due to the rotation of the platen, whereby a feeding of the cut sheet paper to the printing position can be carried out. The pressure roller can be selectively separated from the platen by the mechanical switching system.
The mechanical switching system includes a switching lever which is movable between first and second positions. When the switching lever is at the first position, the pressure roller is separated from the platen so that, even though the cut sheet paper is introduced into the second paper guide path, the feeding of the cut sheet paper to the printing position is prevented. Also, when the switching lever is at the first position, the operative connection between the pin-belt tractor and the drive motor is established so that only the feeding of the continuous form paper to the printing position is ensured. On the contrary, when the switching lever is at the second position, the pressure roller is resiliently pressed against the platen, and the operative connection between the pin-belt tractor and the drive motor is cut, whereby only the feeding of the cut sheet paper to the printing position is ensured.
The paper feeding apparatus as mentioned above is complex and costly, because the mechanical switching system thereof must be constructed by many mechanical parts or elements. Especially, the assembly of a mechanical arrangement for separating the pressure roller from the platen is troublesome due to a coextension of the pressure roller with the platen, resulting in a rise in cost of the assembly thereof.